Rare earth metal organic coordination polymer as well as preparation method and application thereof

Abstract

The invention discloses a rare earth metal organic coordination polymer and a preparation method and application thereof, the rare earth metal organic coordination polymer comprises a rare earth-organic framework material [La (H2-DHTA) 1.5 (H2O) 4] n, and the rare earth metal organic coordination polymer is characterized in that the molecular formula of the rare earth metal-organic framework material is [La (H2-DHTA) 1.5 (H2O) 4] n. The rare earth-organic framework material provided by the invention has good condensation reaction catalytic activity. The compound can be used as a catalyst for rapid synthesis of imidazole compounds such as 2-phenyl-1H-benzo [d] imidazole.

Description

Technical Field

[0001] The invention belongs to the technical field of metal organic framework materials, and in particular relates to a rare earth metal organic coordination polymer and a preparation method and application thereof. Background Art

[0002] In the chemical industry, imidazole compounds are important pharmaceutical intermediates and raw materials for the fine chemical industry. Their synthesis methods have attracted much attention. However, the current synthesis of such compounds requires strong acid or base catalysis, which involves many environmental issues. Therefore, studying simple and efficient synthesis methods for imidazole compounds has become an urgent problem to be solved.

[0003] At present, the main method in the domestic fine chemical industry is precious metal catalysts, but these methods have disadvantages such as high cost, low yield and poor selectivity. Rare earth metal organic coordination polymers are environmentally friendly, with high catalytic yield, good selectivity and mild conditions. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the existing defects and provide a rare earth metal organic coordination polymer and a preparation method and application thereof to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a rare earth metal organic coordination polymer, comprising a rare earth-organic framework material [La(H2-DHTA)1.5(H2O)4]n, wherein the molecular formula of the rare earth metal-organic framework material is [La(H2-DHTA) 1.5 (H2O)4] n .

[0006] Preferably, said n is an infinite structure, and said n is a natural number.

[0007] A method for preparing a rare earth metal organic coordination polymer comprises the following steps:

[0008] Step 1: adding organic ligand 2,5-dihydroxyterephthalic acid into deionized water, and adjusting the pH value of sodium hydroxide solution to 5-6;

[0009] Step 2: then adding water-soluble lanthanum salt;

[0010] Step 3: Perform a hydrothermal reaction to obtain a rare earth metal-organic framework material La-MOF.

[0011] Preferably, 10 ml of deionized water is added per mmol of 2,5-dihydroxyterephthalic acid; and / or a strong base is used to adjust the pH value.

[0012] Preferably, 9 ml of deionized water is added to the amount (mmol) of 2,5-dihydroxyterephthalic acid.

[0013] Preferably, NaOH aqueous solution is used to adjust the pH value.

[0014] Preferably, the water-soluble lanthanum salt is lanthanum nitrate, blue sulfate or lanthanum green; and / or, the aqueous solution lanthanum salt is lanthanum nitrate.

[0015] Preferably, the hydrothermal reaction temperature is 130-140° C., and / or the hydrothermal reaction time is 96 hours; the hydrothermal reaction temperature is 135° C., and the cooling rate after the hydrothermal reaction time is 5° C. / h.

[0016] Preferably, the crystallization time is 48 hours, and the drying is carried out at a temperature of 50-80° C. for 20 hours.

[0017] A rare earth metal-organic framework material La-MOF is used in condensation catalysis.

[0018] Compared with the prior art, the present invention provides a rare earth metal organic coordination polymer and its preparation method and application, which have the following beneficial effects: the rare earth-organic framework material provided by the present invention has good condensation reaction catalytic activity. It can be used as a catalyst to quickly synthesize imidazole compounds such as 2-phenyl-1H-benzo[d]imidazole. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 is the coordination environment diagram of the complex (symmetry code of the complex: #1x, y, -1+z; #21+x, y, z; #3-x, 1-y, 1-z);

[0021] Figure 2 is the three-dimensional structure diagram of the complex;

[0022] Figure 3 is the infrared spectrum of the coordination polymer;

[0023] Figure 4 is the thermogravimetric curve of the complex;

[0024] Figure 5 It is the diagram of the condensation reaction equation;

[0025] Figure 6 It is the side reaction equation diagram of condensation reaction;

[0026] Figure 7Tetrahydrofuran was used as solvent for the condensation reaction. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] See also Figure 1-7 The present invention provides a technical solution: a rare earth metal organic coordination polymer, comprising a rare earth-organic framework material [La(H2-DHTA)1.5(H2O)4]n, wherein the molecular formula of the rare earth metal-organic framework material is [La(H2-DHTA) 1.5 (H2O)4] n .

[0029] In the present invention, preferably, the n is an infinite structure, and the n is a natural number.

[0030] A method for preparing a rare earth metal organic coordination polymer comprises the following steps:

[0031] Step 1: adding organic ligand 2,5-dihydroxyterephthalic acid into deionized water, and adjusting the pH value of sodium hydroxide solution to 5-6;

[0032] Step 2: then adding water-soluble lanthanum salt;

[0033] Step 3: Perform a hydrothermal reaction to obtain a rare earth metal-organic framework material La-MOF.

[0034] In the present invention, preferably, 10 ml of deionized water is added per mmol of 2,5-dihydroxyterephthalic acid; and / or a strong base is used to adjust the pH value.

[0035] In the present invention, preferably, 9 ml of deionized water is added to the amount (mmol) of 2,5-dihydroxyterephthalic acid.

[0036] In the present invention, preferably, NaOH aqueous solution is used to adjust the pH value.

[0037] In the present invention, preferably, the water-soluble lanthanum salt is lanthanum nitrate, blue sulfate or lanthanum green; and / or, the aqueous solution lanthanum salt is lanthanum nitrate.

[0038] In the present invention, preferably, the hydrothermal reaction temperature is 130-140° C., and / or the hydrothermal reaction time is 96 hours; the hydrothermal reaction temperature is 135° C., and the cooling rate after the hydrothermal reaction time is 5° C. / h.

[0039] In the present invention, preferably, the crystallization time is 48 hours, and the drying is carried out at a temperature of 50-80° C. for 20 hours.

[0040] A rare earth metal-organic framework material La-MOF is used in condensation catalysis.

[0041] Embodiment 1

[0042] Metal-Organic Framework (MOF) is a type of crystalline porous material with a periodic network structure formed by the self-assembly of inorganic metal ion centers (metal ions or metal clusters) and bridging organic ligands. It is usually a microporous network coordination polymer formed by self-assembly of transition metals and multi-dentate organic ligands containing oxygen, nitrogen, etc. (mostly aromatic polyacids and polybases). Metal-organic framework materials not only have infinitely variable topological structures, but also have attractive application potential in many aspects such as gas adsorption and separation, catalysis, optoelectronic and magnetic materials, sensors, etc. It is rapidly developing into a research hotspot in many fields.

[0043] MOF has a variety of nano- and micro-scale skeleton-type regular pore structures, ultra-large specific surface area and porosity (up to 0.9) and low solid density, which makes it have many advantages such as large adsorption capacity, high selectivity, easy regeneration and recovery. It can be used as an epoxy resin curing agent for imidazole compounds, and can improve the mechanical properties of products such as bending, stretching, and compression, improve the electrical properties of insulation, and improve the chemical resistance of chemical agents. It is widely used in computers and electrical appliances; as a copper rust inhibitor, it is used in printed circuit boards and integrated circuits;

[0044] It is used as a pharmaceutical raw material for the manufacture of antifungal drugs, antifungal agents, hypoglycemia treatment drugs, artificial plasma, trichomonas treatment drugs, bronchial asthma treatment drugs, anti-rashes agents, etc.; it is used as a pesticide raw material for the synergist of boric acid preparations, and for the preparation of insecticides and fungicides; in addition, imidazole is also used as a raw material for urea-formaldehyde resin curing agents, photographic drugs, adhesives, coatings, rubber vulcanizers, antistatic agents, etc.; it is also an organic synthesis intermediate.

[0045] Embodiment 2

[0046] Research on coordination polymers is mostly focused on transition metal elements. The special electronic structure and unique properties of lanthanide metal elements have attracted the attention of many researchers. More and more coordination polymers and supramolecular structures based on lanthanide elements have been synthesized, and their properties have increasingly attracted the attention of researchers. At the same time, the interaction between lanthanide elements and transition metal elements to obtain 3d-4f coordination polymers has also attracted much attention due to its unique catalytic activity. my country has abundant rare earth resources. In-depth research on the molecular assembly and related properties of rare earth coordination polymers is of great significance to fully utilize the advantages of rare earth resources and develop rare earth high-tech industries.

[0047] The properties of lanthanide metals are ultimately determined by the arrangement of their electrons outside the nucleus. n 5d 0 6s 2 configuration (n = 0-14). Compared with the characteristic d electrons of transition metal elements, the characteristic f electrons of lanthanide elements determine the structural characteristics of coordination polymer materials based on them. Lanthanide elements and transition elements have significant differences due to their different electronic configurations. 3+ Although ions can lose electrons in the 4f orbital, they are fully shielded by the outer layer 5s26p6 and are therefore not used in most reactions. However, the atoms and ions of d-block transition elements have unshielded characteristic d electrons in the valence shell, which are easily affected by the environment and participate in bonding. Therefore, lanthanide metals exhibit significantly different properties from d-block transition metals in the coordination process; at the same time, although lanthanide ions have different numbers of inner-layer 4f electrons, their chemical properties are very similar.

[0048] Lanthanide metals have many excellent properties. In production practice, lanthanide metals are widely used in the production of fluorescent materials, rare earth metal hydride battery materials, electric light source materials, permanent magnet materials, hydrogen storage materials, catalytic materials and precision ceramic materials.

[0049] Embodiment 3

[0050] Compared with transition metals, the research on framework structures based on lanthanide metal ions is still relatively superficial. In fact, on the one hand, due to the high coordination number, lanthanide metal ions need to coordinate with liquids in addition to forming organic ligands to meet the requirements of high coordination number; on the other hand, its relatively more flexible coordination environment is more likely to destroy the original framework premise and carry out partial reorganization.

[0051] The research on lanthanide metal coordination polymers is relatively late and not as thorough as that on transition metals. This may be related to the high coordination number and variable coordination modes of lanthanide metals in coordination. Because of these two properties, the design and regulation of lanthanide metal coordination polymers are more complicated and difficult than those of transition metal elements. However, this also provides us with opportunities to obtain more new and diverse structures.

[0052] A common coordination form of lanthanide metals.

[0053] Most lanthanide metal coordination polymers adopt an eight-coordination mode.

[0054] Lanthanum-organic framework polymer {[La(DHTA) 1.5 (H2O)3]·H2O} n The catalytic activity of lanthanide metal ions was used to investigate the 1.5 (H2O)3]·H2O} n The catalytic activity in condensation reactions, specifically, the catalytic activity in the condensation reaction of o-phenylenediamine and benzaldehyde to form imidazole.

[0055] About coordination polymer {[La(DHTA) 1.5 (H2O)3]·H2O} n Description of the drawings:

[0056] Figure 1 Coordination polymer {[La(DHTA) 1.5 (H2O)3]·H2O} n The asymmetric structural unit is a lanthanum (III) central ion. Lan (III) is an octahedral distorted dodecahedron, specifically composed of six carboxyl oxygens and two water molecules, and is formed by 2,5-dihydroxyterephthalic acid as a bridge. Figure 2 The three-dimensional structure consists of layered channels, which also indicates that the catalyzed molecules form polarization in the channels. Figure 3 The infrared characteristic peaks can also indirectly prove the existence of coordination polymers. Figure 4 This is the thermal weight loss diagram of the coordination polymer. It can be seen that the coordination polymer has good thermal stability. At the same time, it can be seen from the heating weight loss gradient that the proportion of the ligand is consistent with the theoretical value.

[0057] Figure 5 is the equation for the condensation reaction of o-phenylenediamine and benzaldehyde. Figure 7This is the gas phase mass spectrum of the condensation reaction using tetrahydrofuran as solvent. This mass spectrum has been confirmed to be located at retention time 8.49 as the condensation intermediate; retention time 9.29 as the product; retention time 10.45 as the by-product. It can be seen that there is only one by-product; by comparing the experiments with N, N-dimethylamide and other solvents, there are at least 2 by-products and the yield is relatively low.

[0058] In the experiment of the present invention, the optimal conditions are: 40 mL of tetrahydrofuran solvent, 20 mg of catalyst, the molar ratio of o-phenylenediamine to benzaldehyde is 2.5:1, the reflux temperature is 50°C, and the reflux time is 1.5 hours.

[0059] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A rare earth metal organic coordination polymer, comprising a rare earth-organic framework material [La(H2-DHTA)1.5(H2O)4]n, characterized in that: The molecular formula of the rare earth metal-organic framework material is [La(H2-DHTA) 1.5 (H2O)4] n .

2. A rare earth metal organic coordination polymer according to claim 1, characterized in that: The n is an infinite structure, and the n is a natural number.

3. The method for preparing a rare earth metal organic coordination polymer according to any one of claims 1 to 2, characterized in that: The steps include: Step 1: adding organic ligand 2,5-dihydroxyterephthalic acid into deionized water, and adjusting the pH value of sodium hydroxide solution to 5-6; Step 2: then adding water-soluble lanthanum salt; Step 3: Perform a hydrothermal reaction to obtain a rare earth metal-organic framework material La-MOF.

4. The method for preparing a rare earth metal organic coordination polymer according to claim 3, characterized in that: For every mmol of 2,5-dihydroxyterephthalic acid, add 10 ml of deionized water; and / or a strong base to adjust the pH value.

5. The method for preparing a rare earth metal organic coordination polymer according to claim 3, characterized in that: 9 ml of deionized water were added to 2,5-dihydroxyterephthalic acid of the amount of substance (mmol).

6. The method for preparing a rare earth metal organic coordination polymer according to claim 3, characterized in that: The pH value was adjusted with NaOH aqueous solution.

7. The method for preparing a rare earth metal organic coordination polymer according to claim 3, characterized in that: The water-soluble lanthanum salt is lanthanum nitrate, blue sulfate or lanthanum green; and / or, the aqueous solution lanthanum salt is lanthanum nitrate.

8. The method for preparing a rare earth metal organic coordination polymer according to claim 3, characterized in that: The hydrothermal reaction temperature is 130-140° C., and / or the hydrothermal reaction time is 96 hours; the hydrothermal reaction temperature is 135° C., and the cooling rate after the hydrothermal reaction time is 5° C. / h.

9. The method for preparing a rare earth metal organic coordination polymer according to claim 3, characterized in that: The crystallization time is 48 hours, and the product is dried at a temperature of 50-80°C for 20 hours.

10. Application of the rare earth metal-organic framework material La-MOF as claimed in any one of claims 1 to 9 in condensation catalysis.

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